1. Field of the Invention
The present invention relates to telecommunications and, more particularly, to a method and system that uses a mobility server to facilitate call handoffs of a multi-mode mobile station from a first wireless network to a second wireless network.
2. Description of Related Art
There is an increased interest in using more diverse types of wireless access technologies for mobile devices. Different wireless access technologies may be used to provide wireless coverage in different geographic areas. In addition, different wireless access technologies may be used to provide different capabilities for transmitting and receiving voice, data, and/or other media. For example, wireless wide area networks (WWANs), which often use wireless access technologies such as CDMA, TDMA, or GSM, typically provide wireless coverage in relatively large geographic areas. However, in many cases, WWANs do not provide good wireless coverage in buildings. In addition, many WWANs have a relatively limited bandwidth for transmitting and receiving media. However, wireless local area networks (WLANs), which may use wireless access technologies, such as IEEE 802.11, Bluetooth, HiperLAN, or HomeRF, have been used to provide wireless coverage in more limited areas, such as the inside of buildings. In addition, WLANs can often transmit and receive media at a higher rate than many WWANs.
With this increased interest in using diverse wireless access technologies to provide wireless coverage has come an increased interest in providing multi-mode mobile stations that can communicate using more than one type of wireless access technology. For example, a multi-mode mobile station may have one interface for communication with a WWAN, using a wireless access technology such as CDMA, and another interface for communication with a WLAN, using a wireless access technology such as IEEE 802.11. Although such multi-mode mobile stations can provide better wireless coverage in more areas by being able to communicate over different wireless networks, they do not necessarily change their network connectivity in a seamless manner. For example, while engaged in a call via a first wireless network, the multi-mode mobile station may move into an area in which the first wireless network no longer provides good wireless coverage but the second wireless network does. In that situation, it would be desirable for the multi-mode mobile station to be able to continue the call via the second wireless network.
Accordingly, there is a need for methods and systems that can facilitate handoffs of multi-mode mobile stations, for example, from a WWAN to a WLAN or vice versa.